1. Field of the Invention
The present invention relates to ventilating systems for tanks. In particular, the present invention relates to apparatus for attaching exhaust fans to a manway in a tank for exhausting gases from a tank and circulating fresh air therethrough.
2. Description of the Related Art
Exhaust and ventilation fans are used in large tanks and other enclosed areas such as sewers in which workers are welding or performing other tasks such as repairing, painting, cleaning, or the like. Commonly such tanks are cylindrical in shape and have two or more manways to enable workers to enter and exit the tank. Such manways are commonly 20 to 24 inches in diameter. When workers are in the tank, a circular fan well known in the art is attached to one of the manways to exhaust air from the manway and pull air into the tank from the other manway or manways. Such ventilating or exhaust fan is normally connected directly to one manway, thus preventing welding or painting hoses or electrical wires for use by the workers inside the tank from being extended through the manway with the fan attached thereto.
There is thus a need for an apparatus for attaching a fan to a manway in a tank or other enclosed area accessible by a manway which enables a worker to extend hoses and electrical wires through the manway having the fan attached thereto.
Exemplary of the patents of the related art are the following: U.S. Pat. Nos. 3,610,524; 4,270,695; 4,285,269; 4,982,653; 5,097,976; 5,386,845; 6,021,543; and 6,168,514; European Patent EPO288781B1 and Japanese Patent JP200238695.